Apparatus for charging storage batteries



Jan. 4, 1938. N. F. AGNEW I APPARATUS FOR CHARGING STORAGE BATTERIES Filed Jan. 14, 1936 INV'ENTOR fi ormanFAg'zeuf QR 1W HIS ATTORNEY -55 part i" of the casing Patented Jan. 4, 1938 04.! APPARATUS FOR CHARGING STORAGE Norman F. Agnew, Wiitinabnrg, Pa... a-ignortc I The Union Switch Signal company, Swisstionoil' m lfl vale, Pa., a corpora Application January 14, 1, Serial No. 59.035 6 Chill!!- (Cl. 171-414) My invention relates to apparatus for charging storage batteries.

One object of my invention is the provision of novel and improved means for automatically deli creasing the rate of charge of a storage battery when the battery becomes substantially fully charged.

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view partly in elevation, partly in section, and partly diagrammatic illustrating one form of apparatus embodying my invention. Fig. 2 is aview simll ilar to Fig. 1 showing a modification of the apparatus illustrated in Fig. 1.

Similar reference characters refer to similar parts in both views.

Referring first to Fig. 1, the reference char- 2o acter T designates a transformer, the primary i of which is constantly connected with the terminals X and Y of a suitable source of current not shown in the drawing, and the secondary 2 of which is constantly connected with the input terminals 3 and 4 of a full wave rectifier R. The

output terminals 5 and 6 of rectifier R are connected with the terminals of a storage battery B of the usual type in series with a resistance I. The value of the resistance I is such that when this resistance is included in the charging circuit, the battery will be charged at a relatively low rate, but that, if this resistance is short circuited, the battery will then be charged at a relatively rapid rate.

Associated with the battery B is a switch 8 embodying my invention for at times short circuiting the resistance I. This switch is adapted to be operated by gas pressure caused by the gassing of the battery when the battery becomes approximately fully charged as will be explained more fully hereinafter, and in the form here shown, this switch comprises a casing 8 consisting of a hollow lower part 8 which is adapted to be screwed into one of the usual filler cap openings 9 in the battery B, and a hollow upper part 8" which is bolted to the lower part 8' by means of bolts Iii. Clamped between the lower and upper parts 8 and 8 of the casing 8 is a flexible diaphragm ll of suitable material, such for example as rubber, which diaphragm divides the inside of the casing into an upper compartment 8" and a lower compartment 8. Disposed within the upper compartment 8 is a lever l2, one end of which is pivotally attached at point l2- to the 8, and the other end of which carries a spherical part it which rests on the upper side of the diaphragm ii in such manner that vertical movement of the diaphragm Ii will cause rotation of the lever i2 between a lower extreme position in which it is shown in the drawing and an upper extreme position. A mercury contact ll of the usual and well-known construction is secured to the lever l2 by means of a clamp fl in such manner that this contact will be closed or open according as the lever l2 occupies its lower or upper extreme position, and the terminals of this contact are secured by means of flexible connectors l5 and I0 with terminal posts i1 and II which are mounted in the top'of the part 8" of the casing Ii. The terminal posts I! and it, in turn, are connected with the opposite ends of the resistance I, and it will be seen, therefore, that the resistance I will be short circuited by the contact ll when the lever i2 occupies its lower position in which it is shown in the drawing, but not when this lever occupies its upper position.

The lower part 8 of the casing 8 is provided with two vents 2| and 22 which connect the compartment 8 with the outer atmosphere, The vent 2| is normally closed by a gravity operated safety release valve 23, and is of such size that when this vent is open, any gases which are generated in the battery B .due to the charging current at any state of charge of the battery can escape through this vent sufficiently rapidly to prevent any appreciable pressure from building up in the compartment 8. The valve 23 is so constructed that it will open when and only when the gas pressure in the compartment 8 exceeds that required to move the diaphragm ii upwardly to the position in which the contact i4 is opened. The vent 22 is of such size that any gases which are generated in the'battery B due to the charging current wheii the state of charge of the battery is below that at which the battery begins to gas rapidly will be permitted to escape through this vent at a rate which will prevent any appreciable pressure from building up in the compartment 8*, but that, the gases which are generated due to the charging current when the battery becomes charged to the potential at which it begins to gas rapidly will cause sumcient pressure to be built up in the compartment 8 to force the diaphragm ii upwardly to the position in which the contact ll opens.

The operation of the apparatus shown in Fig. 1 as a wholeis as follows: A cell on chargewill begin to gas at about two and three tenths volts. The point of gassing depends upon the voltage.

but the amount of gassing depends upon the current. At high rates of charge, the battery will be about 80 per cent fully charged when it starts to gas rapidly, but at lower rates of charge the percentage of charge at which the battery begins to gas rapidly will be higher. It

' prising a winding II mounted will be seen, therefore, B is discharged below that when the battery the state of charge at which it begins to gas rapidly. the battery, if it gases at all, will gas at too slow a rate to cause sumcient pressure to build up in the compartment I to open the contact II, and as long as this contact remains closed, the resistance: 1 will be short circuited, thus causing the battery to be charged at the high rate. As soon, however, as the battery becomes charged to the state of charge where it ;begins to gas rapidly, the pressure in the compartment 8 will then build up to a value which is sumcient to force the diaphragm ll upwardly and open the contact is. The opening of this contact will remove the short circuit i'rom the resistance 1, and as a result, the charging current will then become automatically decreased to the low rate. A slight amount of gassing will hold the diaphragm H in its upper position after it has once been moved to this position, and the parts are so proportioned that the amount of gassing which takes place of charge will be sumcient charged. If, however, the cell becomes discharged to the point where the battery quits gassing rapidly, enough sas will escape from the vent 22 to allow the diaphragm to move downwardly to the position in which contact ll becomes closed. The closing of contact-ll will, of course, cause the charged at the high rate. It will be seen, therefore, that with apparatus embodying my invention, it is possible, by properly-proportloning the to maintain the battery at its approximately fully charged value regardless of the manner in which the load on the battery varies without danger oi damage to the battery.

Referring now to Fig. of the apparatus here switch 8 which is of somewhat dlilerent dedan from the switch 8 shown in Fig. 1. shown, the switch S includes a 2, 1n the modified form relay C comon an inverted U-shaped magnetizable core 2. which is secured tothepartl ofthecaslnglwithinthe compartment F. The relay 0 also comprisesan armature 21 which is attached to one leg of thecorefli'orswingingmovementtcwardand away from the other leg of the core. One terminal of winding 2! of-relsycisconnected with a terminal post II which is mounted in the part.'

with the terminal post ll. 28, in turn, is connected with nal oi the battery B through it will be seen, therefore. that 2! is closed, the winding 25 supplied with current from that, when the switch 20 is battery to again become illustrated,Iemploya- 'Asher e' of the casing, and relay is connected The terminal'post the positivetermionce it is moved there. It follows, therefore, that when the armature is once picked up it will remain picked up until the switch 20 is opened to deenergize the winding 2|.

The armature 21 carries a contact member II which is secured to, but insulated from, the armature, and this contact member cooperates with a used contact member I! secured to. but insulated from, the core 20, to form a contact Il-sl which is closed or open according as the armature occupies its released position in which it is shown in the drawing, or its attracted position.- The contact Il-Il is adapted to take the place of the mercury contact I shown in Fig. 1, and to this end the contact member 3! is electrically connected by means oi the flexible connector I! with the terminal post ll, while the contact member II is electrically connected by means of a connector Ill with the terminal post II. It will be seen, therefore, thatthereslstmcelwillbeshortcircuitedby the contact il-fl'when the armature 21 is released,butnotwhenthisarmstureispickedup.

Thearmaturefl alsocarriesadependingarm 21- which cooperates with theupper end of an operating rod 12 which is secured to the diaphragm II, the parts being so proportioned that upward movement of the diaphragm ll due to gaspressureinthecompartmentl willmove the armature from its released position to its attracted position. The lower end of the operating rod 32 is operatively connected with a safety release valve 88 which controls the ucape of gas from the compartment 0* to atmosphere through the vent II. The parts are so proportioned that the valve closed by gravity, but that, when the diaphragm II is moved-upwardly to the position in which the armature I! occupies its attracted position, theoperatingrodllwillopenthisvalve.

Theoperationdtheapparatusshownlnflgj is as follows: When the relay 3 is discharged filler cap openings oi One advantage of apparatus embodying my invention is that it insures that the battery will be maintained at a state of maximum charge at all temperatures. 1

Another advantage of apparatus embodying my invention is that a large amount of power is available for operating the pressure operated switch, and this power is independent of temperature, vibration, relay iron variations, small marginal differentials, etc.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, claim is: 5

1.1a combination, a. storage battery, a resistance, charging means for said battery connected with said battery in series with said resistance, a first contact, a switch comprising a two part hollow compartment the lower part of which is adapted to be screwed into one of the illler cap openings of said battery, a flexible diaphragm clamped between the two parts of said casing and dividing said casing into an upper and a lower compartment; a relay mounted in said upper compartment, said relay being provided with a winding which is connected with said battery in series with said first contact, with an armature which is movable between an attracted and a released position, and with a contact which is open or closed according as said armature occupies its attracted or released position, the parts being so proportioned that the current which flows in said winding when said first contact is closed will be insuflicient'to move said armature from its released to its attracted position but will be sumcient to retain said armature) in its attracted position after it is moved there; means for operatively connecting said armature with said diaphragm in such manner that said armature will be moved from its released to its attracted position in response to movement of said diaphragm from a lower to an upper position, a vent for venting the lower compartment of said casing to atmosphere, a relief valve for closing said vent biased to a closed position, means for operatively connecting said release valve with said diaphragm in such manner that movement of said diaphragm to its upper position will move said release valve to its open position, and means for connecting said relay contact in multiple with said resistance.

2. In combination, a storage battery, 9. resistance, charging means for said batteryconnected with said battery in series with said resistance, a first contact, a switch comprising a two part hollow compartment the lower. part of which is adapted to be screwed into one of the said battery, 9. flexible diaphragm clamped between the two parts of said casing and dividing said casing into an upper and' a lower compartment,"a relay having its winding connected with said battery in series with said first contact, a second contact controlled jointly by said relay and said diaphragm, means tor connecting said second contact in multiple with said resistance, and means for venting said lower compartment to atmosphere when and only when said diaphragm is moved to the position in which said second contact is open.

3. In combination, a storage battery,

what I a resistance, charging means for said battery connected with said battery in series with said resistance, a switch comprising a two part hollow compartment the lower part of which is adapted to be screwed into one of the tiller cap openings of said battery, a flexible diaphragm clamped between the two parts oi. said casing and dividing said casing into an upper and a lower compartment, a relay having its winding at times supplied with current from said battery, a normally closed contact controlled jointly by said diaphragm and said relay in such manner that said contact will become opened if and only ii! said diaphragm is moved from a lower to an upper position but that when said. contact once becomes opened it will subsequently be held open by said relay, means for connecting said contact in multiple with said resistance, and means controlled by said dia- Dhragm for controlling the gas pressure in said lower compartment.

4. In combination, a storage battery, a resistance, charging means for said battery connected with said battery in series with said resistance, a switch comprising a two part hollow compartment the lower part of which is adapted to be screwed into one of the filler cap openings of said battery, a flexible diaphragm clamped between the two parts of said casing and dividing said casing into an upper and a lower compartment, a relay having its winding at times supplied with current from said battery, a normally closed con-, tact controlled jointly by said diaphragm and said relay in such manner that said contact will become opened if and only if said diaphragm is moved from a lower to an upper position but that when said contact once becomes opened it will subsequently be held open by said relay, meansfor connecting said contact in multiple with said resistance, and means for venting said lower compartment to atmosphere when and only when said diaphragm is moved to the position in which said contact is open. v

5. In combination, a storage battery, a switch, a relay provided with a winding which is connected with the terminals of said battery over said switch and with an armature which controls a contact in such manner that said contact will be closed or open according as said armature is released or picked up, the parts being so proportioned that the current supplied to said winding-wil1 be insufllcient to pick up said armature but will be suiiicient to hold said armature picked up once it is moved to its picked up position, charging means for said battery controlled by said contact, and means controlled by the gassing rate of said battery for at times moving said armature to its picked up position.

6. In combination, a storage battery, a switch, a relay provided with a winding which is connected with the terminals of said battery over said switch and with an armature which controls a contact in such manner that said contact will be closed or open according as said armature is released orv picked up, the par s b in so P op tioned that the current supplied to said winding will bev ins'uflicient to pick up said armature but will be suillcient to hold said armature picked up once it is moved to its picked up position, means for charging said battery at a relatively low or a relatively high rate according as said contact is open or closed, and means for mechanically moving said armature to its picked up position when said battery begins to gas at a relatively rapid rate.

NORMAN F. AGNEW. 

